Oil and other liquid petroleum products into water of land

Oil Spill is the accidental or wilful release of crude oil and other liquid petroleum products into water of land. The term has acquired a very sinister meaning and an oil spill generally means an environmental disaster with innumerable animals and plants generally wasting away due to the harmful effects of pollution. While oil spill does not cause immediate death or destruction to life and property like other disasters such as hurricanes and earthquakes, the effects of an oil spill can linger for a long time and continue harming generations of living things. The paper examines various aspects of oil spills such as the damage to marine life, methods utilized for spill containment, their effectiveness and also examines a few major oil spills that have occurred recently.

Ecological Risk Assessment of Oil Spill
Weins (2007) has proposed a model for the ecological risk assessment to evaluate the damage that is caused to the environment due to oil spills. The author contends that when a large oil spill occurs, many arguments take place about the damages caused by the spill and the accusations, denials and heated discussion take place on the amount of damage that has been caused. The author has suggested that the ecological risk assessment of the damage can be predictive and retrospective. In the predictive system, the effects of oil spills, pipeline bursts, building of nuclear reactors are estimated and forecasted as accurately as possible. Retrospective is the calculation of the effects of an oil spill that has already taken place. According to Wiens, the ecological risk assessment is done in three phases and they are explicit formulation of the problem, analysis phase and the characterisation of the risk phase. In the explicit formulation of the problem phases, is created as a hypothesis about whether and why certain ecological effects result from specific activities of humans. The anticipated effects are identified clearly with a reference target that states the required condition of the system and the measurable end points. The aim here is to prevent any undirected searches for anything that seems as an effect or vague and . In the analysis phase, the exposure to stressors and the possible ecological effects are identified and evaluated. It is not presumed that the presence of oil will definitely result in ecological degradation. Such relationships are assigned with a probability of occurrence when doing so is not possible, the plausibility of the relationship should be assessed. A characterization of the risk is the phase the likelihood that a stressor actually caused a specific ecological effect and this s evaluated. Certain inherent uncertainties in the measurement of the parameters, confusing data, any natural variations and others are also assumed. This method produces a reasoned, logical objective and either proves or disproves that a particular effect was caused by a certain ecological problem.

The author has applied this model to understand the effects of the Exxon Valdez oil tanker spill that occurred in the Alaskan region. The effects of the oil spill on a species of ducks called the Harlequin ducks were formulated and the author attempted to trace out the immediate and residual effects of the oil on the birds. The area of the spill included almost eight hundred kilometres of the shore line including a number of small inlets and streams. Weins (2007) has claimed that in the region of the direct spill, the population of the ducks fell very steeply. In addition, other areas that actually did not receive any spill also faced a decline in their mating and population patterns. A schematic of the model as applied is shown in the following illustration.

Causal Linkages of effects of oil spill on Harlequin Ducks (Weins (2007)
Figure 1. Causal Linkages of effects of oil spill on Harlequin Ducks (Weins (2007)
Weins has argued that when spills occur, the whole food chain gets affected and its not just one specifies that suffers. In the above illustration, mussels that form the food of ducks accumulate the oils and the ducks that eat the mussels are also effected. In addition, they also encounter the oil on the water and on the shore and thus the birds suffer from this mode also. The ingestion of the mussels leads to increased hydrocarbons in the bodies of the ducks and they suffer from lack of reproduction as either the makes are not able to produce the required sperm count or the eggs have fragile shells and cannot hatch.

Assessment Stages of Damages caused by Oil Spills
Boehm (et all, 2007) has written about the stages involved in the risk assessment of exposure due to oil spills. The authors argue that the effects of the oil spill results in a number of complex changes that happen over many molecular, spatial and temporal scales. The nature and extent of exposure of biological resources to spilled oil components or the exposure assessment is important for the ecological risk assessment and the related natural resource damage assessment investigative frameworks. According to the authors, the important factors of an oil spill that have form the critical effects of the spill are the chemical and physical properties of the oil; the pathways that take oil and its component chemical compounds to a receptor; the ways in which these receptors encounter and interact with the spilled oil; the background exposure or the to the same chemicals as found in petroleum that is unrelated to the spill, but present in the environment in the spill area. The release of oil into water depends on the type of oil spilled; mixing energy such as waves, wind; release location; possible changes in exposure as a result of the use of chemical countermeasures such as dispersants. Light, refined products such as gasoline evaporate quickly and exposures to its chemical components are short lived and minimal. Heavier fuels and crude oils will weather more slowly with less volatile, but soluble components existing as important stressors. The greatest damages occur in spills of light to middle crude and refined oils.

Osuji (et all 2007) have written about the time factors that are involved in oil spills. They speak of different stages of time frames in an oil spill and these are briefly mentioned as below:

Stage 1. Spill in progress 0 to 14 days: This period covers the time when oil is on the surface of the water and is likely to have its maximum exposure potential as a substance on the sea surface, potentially intersecting with seabirds and marine mammals.
Stage 2. Cleanup period 1 to 24 months: In this period, oil has largely moved from the water surface to a shoreline with sub tidal sediments. In this period a maximum concentrations and exposure potential may occur along the shorelines and in . Activities such as natural events such as wave energy and physical removal; biodegradation and human cleanup occur and oil residues are left to naturally degrade and otherwise weather.
Stage 3. Recovery period 24 months to 10 years or more: In this time period and after the cleanup standards are achieved, impacted resources may recover or be in the process of recovering, even as remnants of the spill may remain in the system as isolated deposits of weathered oil. The definition of recovery is the return to baseline services and conditions, where baseline services should reflect conditions that would have been expected at the assessment area had the discharge of oil not occurred, taking into account both natural processes and those that are the result of human activities. Recovery is also defined as the return of a species or population to a state that would have existed if the spill had not occurred, taking into account natural variability and uncertainty in the environmental parameters being measured Because environments are in a constant state of change due to ongoing natural and human factors, the definition of recovery as a return to pre-spill conditions is not valid because natural change would occur over time whether the spill had taken place or not (Osuji, et all 2007).
Environmental disasters as risk regulation catalysts
Kahn (2007) has suggested that it only when environmental disasters occur that the government and organization wake up and try to bring in regulatory control. The author suggests that unexpected events such as environmental catastrophes capture wide public attention. Soon after such shocks, new regulation is often enacted. He argues that for 15 years the Congress spent labouring in vain to produce a national oil-spill liability law. Some believed that it would take a catastrophic oil spill to break the legislative stalemate. In 1989 The largest spill in U.S. history occurred when the Exxon Valdez dumped more than 40 million gallons of oil into Alaskas Prince William Sound. It took a disaster of that magnitude to get both chambers to pass bills that set up a national program to parcel out financial responsibility for oil spills and to pay for cleanup and damages. Big shocks educate the rationally ignorant voter, leading to pressure for legislative or regulatory reform. Under the Oil Pollution Act of 1990, the owner or operator of a facility from which oil is discharged is liable for the costs associated with the containment or cleanup of the spill and any damages resulting from the spill.

Methods employed in Cleaning Oil Spills
Mona (et all, 2007) has proposed a number of methods that can be employed for cleanup operations of oil spills. The author suggests that oil sheen cannot be cleaned but they only be dispersed by using detergents. The detergents make the oil to settle down but this creates pollution on the seabed. Some types of equipment that are used are Absorbent Boom, Sausage Containment Boom, Skimmers, Snares and others. Bioremediation where biological agents are employed to remove oil; burning which can be done only when there are no strong winds, the sea is calm and the oil has not dispersed; use of dispersants that work like detergents. The author suggests that the detergents cluster around oil globules and allow then to be carried by water but it only help the oil to spread to a wider region. But dispersed oil globules are heavier than water and would sink to the ocean floor, causing more damage.

Harris (et all, 2007 ha suggested that the ill effects of pollution and hazardous wastes are not gone even after twenty five years. The authors revisited and examined a hazardous waste location that had been sealed about twenty-five years back and found that the local population, the animals and plants in the surrounding area had suffered from traces of the wastes that had mingled with the ground water and had percolated into the drinking water, the food chain and plants and animals showed stunted growth.

Some Notable Oil Spills in recent history
Anthony (et all, 2006) has provided details on some great oil spills in the past few decades since oil was transported through large oil tankers. The following table provides details of a few important ones.

Table 1. Major Oil Spill Disasters (Anthony, et all, 2006)

Spill / Tanker Location Date Tonnes of crude oil
Gulf War oil spill Persian Gulf January 23, 1991 136,000 1,500,000
Ixtoc I oil well Gulf of Mexico June 3, 1979- March 23, 1980 454,000 480,000
Atlantic Empress / Aegean Captain Trinidad and Tobago July 19, 1979 287,000
Fergana Valley Uzbekistan March 2, 1992 285,000
Nowruz oil field Persian Gulf February 1983 260,000
ABT Summer 700 nautical miles (1,300 km) off Angola 1991 260,000
Castillo de Bellver Saldanha Bay, South Africa August 6, 1983 252,000
Amoco Cadiz Brittany, France March 16, 1978 223,000
Amoco Haven tanker disaster Mediterranean Sea near Genoa, Italy 1991 144,000
Odyssey 700 nautical miles (1,300 km) off Nova Scotia, Canada 1988 132,000
Sea Star Gulf of Oman December 19, 1972 115,000
Torrey Canyon Scilly Isles, UK March 18, 1967 80,000 119,000
Irenes Serenade Navarino Bay, Greece 1980 100,000
Urquiola A Corua, Spain May 12, 1976 100,000
Conclusion
The paper has examined various aspects related to oil spills and has discussed the ecological risk assessment of oil spills that help in estimating the possible harms caused by oil spills to the environment and the assessment stages of damages caused by oil spills. Various methods employed in cleaning up oil spills have also been discussed and the question if ecological disasters are required to force the government to bring in legislation have also been asked. The paper has also provided details on some major oil spills.